Sample size calculator

How many respondents should you have for a successful survey? Determining the sample size of your survey can be exhausting. But we make it simple! Use Voxco’s sample size calculator to find the correct sample size for your survey in seconds. Simply put the values, and we’ll calculate the sample size for you. 

Margin of Error Calculator4

Calculate Your Sample Size

Population Size

Confidence Level

Margin of Error


The sample size calculator can help you mitigate human error and calculate the sample size faster. 

What is sample size?

Sample size is defined as the number of completed responses you get in your survey. Because it merely reflects a portion of the group of people (or target population) whose ideas or behavior you care about, it’s termed a sample. For example, a “random sample” is a method of sampling in which respondents are picked purely by chance from the general population. 

In research, sample size is the number of people included in the study to reflect a population. The size represents the overall number of respondents present in the study. This number is often split into sub-groups based on demographics such as age, gender, and location to ensure that the total sample accurately represents the entire population. 

Determining the optimum size is one of the most important aspects of statistical analysis. The results will not be valid if a small sample size is selected. The size can be calculated by hand using the formula we mention next or by using a sample size calculator.

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How to calculate the sample size?

You can use the following formula to determine the correct sample size your research should have. 

Sample size calculator Sample size calculator


Sample size calculator Sample size calculator

N is the number of people in the population.  

z = z-score, i.e., desired confidence level

e = margin of error (% in decimal form)

The z-score represents the number of standard deviations a proportion is distant from the mean. Refer to the chart below to determine which z-score to use. 

Example: If you want to use a 95 percent confidence level, standard deviation of 0.5, and confidence interval (margin of error) of 5%, you can simply change the values in the formula:

e = ((1.96)2 x .5(.5)) / (.05)2 

e = (3.8416 x .25) / .0025 

e = .9604 / .0025 

e = 384.16 

Your sample size should be 385. 

Before you start calculating the right size of respondents, you should learn more about specific nuances. 

  1. Margin of Error or Confidence Interval
  2. Confidence Level
  3. Population Size
  4. Standard Deviation

Let’s discuss these three factors in brief. 

1. Margin of Error or Confidence interval: 

The margin of error indicates how certain you may be that the findings of a study match what you would expect to discover if the population being investigated could be surveyed. Usually, the confidence interval is expressed as a plus or minus number. If your confidence interval is 7 and 70% of your sample chooses a response, you can be certain that if you surveyed the entire population, 63 percent (70-7) and 77 percent (70+7) would choose that response. 

2. Confidence level: 

The percentage will tell you how confident you can be that the actual population taking your survey will choose an answer from the available options. It’s expressed as a percentage and indicates how often the percentage of people choosing a particular response falls inside the confidence interval. 

For example, a 99 percent confidence level suggests that if you repeat a poll repeatedly, your results will match those of a population 99 percent of the time. 

3. Population Size:

Population size is the total number of audience you want to gather data on, the total no. of people you wish to survey. For example, if you want to collect data from Japanese residing in Australia, your population size would be approx—93.5 thousand (as of October 2021). 

4. Standard deviation: 

The standard deviation, which gauges a data set’s distribution from its mean, is another essential factor to consider when calculating sample size. The standard deviation can be used to estimate how much the replies you receive will differ from each other and the mean when determining the sample size. We can use a sample’s standard deviation to approximate a population’s standard deviation. 

Learning about these factors that affect the statistical significance is better, especially when using a sample size calculator. This will help you uncover where the problem lies and allow you to fix it faster.

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What’s the importance of statistically significant sample size in the result?

The greater the sample size, the more statistically significant the survey results will likely be.  

A larger sample size can help you reduce the margin of error. No matter how carefully you select your sample, you will likely fall victim to the margin of error. However, with a larger sample size, you are likely to gather data that can create an accurate picture of the population and demonstrate statistical significance. 

However, in some cases, even if you don’t have a survey sample size that represents the entire population, survey sampling can still provide useful information. For example, customer feedback is one of the surveys that accomplish this, regardless of whether or not the sample size is statistically significant. 

However, political pollsters must cautiously select a sample size that reflects the entire population. They must ensure that it is balanced and representative of the entire population. To ensure you have a representative sample, use a sample size calculator. Let’s see some other use cases that require you to have a statistically significant sample size. 

  • Employee surveys 

A statistically significant sample size can help you get a more comprehensive picture of your personnel. It’s vital to send the survey even if the sample size isn’t statistically significant. 

  • Customer satisfaction surveys 

Customer satisfaction surveys do not always require a statistically significant sample size. While your responses must be correct and reflect client sentiment, you should truly scrutinize each response in a customer satisfaction survey.

  • Market research 

A statistically significant sample size can quickly assist you in gaining insight into your target market. It also ensures that you’re receiving the most up-to-date data.

  • Determine your sample size.

It is neither ideal to assume many people will participate nor to guess the number of people who will participate. Using a sample size calculator to determine a statistically significant sample size is a good business for any research method. You can also use a survey panel like Voxco Audience to select qualified and vetted participants. This makes it easier to create a statistically significant sample size and gather feedback worldwide. 

Now that you have learned how to choose an accurate sample, all you need to do is conduct your market research.

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This post is also available in French.